Within the framework of Ryōbu Shintō, Amaterasu Ōmikami was understood through the honji suijaku paradigm, in which Buddhist deities are regarded as the original ground (honji) and Shintō kami as their trace manifestations (suijaku). Amaterasu, the sun kami and ancestral deity of the imperial line, was interpreted as the manifest, local appearance of Dainichi Nyorai, the cosmic Buddha at the center of esoteric Buddhist cosmology. In this view, Dainichi represents the ultimate, universal reality, while Amaterasu is that same reality refracted into the specific cultural and mythic landscape of Japan. The two are not separate beings but two perspectives on a single, underlying truth.

This identification was supported by a deep symbolic resonance between the deities. Dainichi Nyorai, whose very name evokes the “Great Sun,” embodies cosmic light, wisdom, and the illuminating power of enlightenment, while Amaterasu governs the physical sun that brings light and order to the human world. Amaterasu’s radiance was thus treated as the concrete, visible expression of Dainichi’s metaphysical brilliance. Even elements of Amaterasu’s cult, such as the sacred mirror, could be read as symbols of the clear, reflective nature of awakened consciousness, without stripping the kami of her distinct Shintō character.

Ritually and doctrinally, this synthesis allowed Buddhist and Shintō practices to interpenetrate. Shrines dedicated to Amaterasu, especially Ise Jingū, were reimagined as earthly counterparts to the sacred spaces of esoteric Buddhism, and Buddhist mantras, rites, and iconography associated with Dainichi were brought into dialogue with Shintō myth and ceremony. At the same time, Amaterasu’s role as the progenitor of the imperial line was reinterpreted in light of Buddhist notions of enlightenment and compassionate activity, giving the imperial cult a cosmic, Buddhist dimension while preserving its native mythic framework.

Through this interpretive lens, devotion to Amaterasu could be experienced simultaneously as devotion to the highest Buddhist principle. The solar kami who orders the visible world and the cosmic Buddha who illuminates all realms were seen as two faces of the same ineffable reality, one articulated in the language of Shintō myth, the other in the symbolism of esoteric Buddhism.